Abstract

Gastric plasmacytoma (GP) is a rare variant of gastric lymphomas. In the exceptional
event that a patient presents with GP, the lesion occupies the mucosal layer in the
vast majority of cases. Here we report a case of nodular plasmacytoma confined to
the submucosa with no evidence of Helicobacter pylori (Hp) infection. The patient was a 59-year old female presenting with no particular
symptoms. The tumor was well-demarcated and consisted of a diffuse monomorphic proliferation
of plasma cells with numerous lymphoid follicles scattered throughout the tumor. The
mucosal surface was intact and not associated with any tumor nodules. The cells were
diffusely positive for CD79a, Bob1, EMA and IgA and consistently negative for CD3,
CD19, CD20, PAX5, CD56, IgM and IgG. Additionally, in situ hybridization demonstrated clonality in the form of λ light-chain restriction. This
submucosal nodular proliferation pattern of plasmacytoma is poorly recognized and
considered to be a novel variant of lymphoma.